Hello, I'm new to the forum. Found y'all while looking for info on 928 transaxle power handling so I won't know the forum conventions. Take this post as a sanity check for myself. I apologize, especially to any Porsche purists for this post. I do respect the design, so much so that I want a great handling, great looking car as a project. I feel that can only be found in a Porsche.


In any case, I've had an idea floating in my head for a long time to take a trashed 944 or 928 (Bad interior, not running, needs serious maintenance, bad modification, bad paint, etc.) and turn it into a project car. By project, I mean a new, modern engine. More than likely a rebuilt N54 or M/N73 (with boost). Additionally, I plan on redoing the interior, as upholstery is something I've been very keen to dip my toes into. Finally, an aero/widebody kit I'll end up fabing by hand.


With all that said, keeping the handling and weight balance of the original car is paramount to me, otherwise I would buy something else. I choose those engines because A. Good power delivery B. Similar weight to the stock engine (M/N73 into 928, N54 to 944) C. Parts are not as rare as parts for a 79 928. I'm aware that the stock transaxle will not tolerate any of the engines listed, and that fitting and mounting these engines will be no small feat.


Currently, I'm looking at a 79 928 with flaking paint, a full cage, gutted interior, a fire extinguisher holder, and a driveline that was likely held at 6 grand for far too long. You think someone raced it?


This isn't my first project, but definitely the largest scope wise, and I have no issue with the car sitting half assembled for a >1 year. I have a decent amount of machining/fab experience, as well as carbon and glass work under my belt. My day job is industrial maintenance/ECE, I basically live to wrench. In terms of budget I'm aiming for $20k - $30k total cost, not including the car itself (3-8k in that case). I'm curious to see perspective on this project. How crazy am I? I've never worked on a Porsche, especially not a car double my age and then some. What issues (apart from the non-Porsche specific ones related to heavy modification of an existing design) will I run into? Thank you for any insight you can share with me.

 

 

Performance/track mods might be your cheapest expense in refreshing a neglected/barn find. Research prices in common wear parts; fuel system, vapor recirc, cats (if used for street, supporting emissions compliance). Considerable parts in these categories have increased in price by a factor of x10.

 

I would venture to say that if you pull the engine and transmission, all that’s left that is Porsche-specific is the body and chassis. There shouldn’t be a ton of unique surprises there if you’re familiar with modifying unibodies. As you probably already know, the body from the doors forward is aluminum.

Everything is so well documented in the factory service literature that you’re probably better off with this platform, other than the inevitable space constraints.

 

My thought is that the 928 platform will teach you a great deal about excellence in analog auto manufacturing.

A 928 chassis is extremely robust and rigid. So much so that a cage is fairly redundant and a waste of time and money for all but racing purposes.

My favorite 928's to drive are the lightweight versions and grabbing an early chassis will start you in the right direction. There are several 928 owners that have installed Corvette transaxles with fabricated mounts by aftermarket suppliers and this is important because the best of the 928 manual transaxles can be overwhelmed by 450 hp. You do not have to re-invent the wheel for the gearbox!

Check out Carl's thread "From empty shell to completed car". it will give you some perspective on an out of this world build.

Regards,

Dave

 

Will be a fun project to follow along on. I'd be surprised if you can do it for $20k though. I've spent more than that on 928s I've driven home.

 

Please don't spend $3k on a rolling shell that someone has raced.

If you take a Cleetus McFarland approach to your build you will have spent $20k (likely much more) on a vehicle that nobody will want to buy from you and that your girlfriend won't want to be driven around in. I doubt a modern BMW motor would fit - a turbo kit or a LS engine swap is the usual approach for those with a lead foot.

If you must have a 928, take your $20k and get a S4 in fair condition (you won't be happy with the performance of anything earlier). By the time you've gotten it to daily driver mechanical condition, you will have spent the other $10k. By that point you will have sunk $30k into a vehicle worth about $20k. Maintenance on the car will set you back about $2k to $3k a year depending on how you operate it. This is an 80's era V8 so it is not cheap on gas. That's the economics of owning a run of the mill 928.

 

Come on in the water is fine!
I have to disagree with the previous post. I love my s4 cars and the GT, but I don’t think you would be ‘disappointed’ with a 1986.5 car. Essentially same power and braking but a bit lighter. Interiors are same…or can be. Personally I think the perfect starting point for a swap would be a 1986.5 with LSD and no rear AC. Fun and fun.Jason

 

So many ways to scratch this itch... All of them involve money or time in various proportion. One thing is for sure, the sooner you buy the more affordable a good or even decent car will be.

928's are not getting any cheaper and the number of mechanics is variable with many aging out and the enthusiasts carrying the ball to varying degrees of success.

As always, buy the best newest car you can... They are cheaper in the along run.

 

Thank you everybody for your insights. Meant to reply sooner but life got in the way.

It’s good to see I’m not totally over the wall with this one.

I have no issues with cutting up the firewall and chassis to make a motor fit. With it being a unibody construction it’s feasible to reinforce the structure with a carbon sandwich. Finding fasteners that won’t corrode is the difficult part, but can be mitigated through good construction.

As I’m unaware of the major costs associated with an older car, could you break it down (general cases) for what these expenses would be? I know rust isn’t a huge issue with these cars, as least the ones I’ve looked at in my area.

 

Thank you for Carl’s thread. I’ve read though quite a lot of it. Lots of good information in there.

And in regards to a corvette transaxle, I’m assuming the half shafts are not the right spline size for the wheels. Is there a kit for these? I could made some, as I have access to a 5 axis Hass currently, but splines really need to be shaped, not milled.

 

The factory automatics can take something like 1000 hp IIRC.

Just refresh it with new seals internally and it should be fine and easily handle whatever engine you throw at it.

I doubt those I6 engines will fit, too long and tall for the 928.